The term 'Irving Berlin Classic' refers to two of the most famous songs written by the American composer Irving Berlin. The first song is 'ALWAYS', a romantic ballad which was released in 1925 and has since become a standard of popular music. The second song is 'Puttin' on the Ritz', a jazz-influenced number which was released in 1929 and has since become an iconic classic. Both songs have been covered by numerous artists over the years and remain popular today.